Thinking about buying a used Mazda CX-9 (2007–2023) in New Zealand? We've documented 28 known faults for this model spanning engine, cooling, suspension, and transmission. Each researched and verified before it's published. The most serious issues here are rated critical. Two are set out in full below — the rest, with the symptoms, repair costs and checks for each, are free with an account.
28
Documented faults
Critical
Most serious
$450–$2,200
Typical repair
7
Systems covered
Known Mazda CX-9 faults
Every fault below is documented specifically for this model — researched and verified before it’s published.
01SkyActiv-G 2.5T Low-Speed Pre-Ignition (LSPI)
CriticalRareEngine $8,000–$18,000 to fix
The turbocharged 2.5T SkyActiv-G engine in early production TC CX-9s is susceptible to low-speed pre-ignition under high torque demand at low rpm, particularly when towing or under hard acceleration from low speed. The detonation event can bend connecting rods or damage pistons catastrophically in a single occurrence. Mazda addressed the issue via revised oil specification mandating 0W-20 SN Plus or SP-rated oil and ECU calibration updates, but engines operated on incorrect oil or missing updates remain at risk.
Symptoms to notice
Sudden catastrophic loss of power under hard acceleration from low rpm
Loud knocking or bang from engine at low rpm under load
Engine warning light immediately after event
Engine will not restart normally after LSPI event
What to check
Confirm service history always used 0W-20 SN Plus or ILSAC GF-6 rated oil — standard 0W-20 without SN Plus rating is insufficient. Check with Mazda dealer for any outstanding ECU calibration update. Inspect for signs of previous engine damage or undisclosed engine replacement.
Where to look: Engine block — pistons and connecting rods, 2.5T turbocharged engine
Ask the seller
“Has 0W-20 SN Plus or ILSAC GF-6 certified oil always been used, not standard 0W-20?”
“Has the vehicle received Mazda's ECU calibration update related to LSPI?”
“Any history of sudden power loss, engine knock, or engine replacement?”
02Electric Power Steering Rack Rattle and Clunk
MinorOccasionalSuspension $1,500–$3,800 to fix
The TC-generation CX-9 uses an electric power steering rack where the internal rack preload spring and torsion bar interface can develop excessive clearance, producing a rattle or clunk transmitted through the steering column at low speeds over broken surfaces. The electric motor and rack assembly is a sealed unit with limited ability to adjust preload in the field, often requiring full rack replacement once internal wear or loose end-of-travel contact points develop.
Symptoms to notice
Clunking or rattling from the steering rack area when traversing rough surfaces or speed humps at low speed
Knock felt through the steering wheel during slow-speed manoeuvring over uneven surfaces
What to check
With the vehicle stationary, rock the steering wheel gently side-to-side at the straight-ahead position and listen for a knocking noise from the rack; drive slowly over a raised kerb entry or rough gravel and listen for a clunk from the steering rack; inspect the intermediate shaft and rack pinion boot for looseness or damage; check for any EPS warning lights on the instrument cluster.
Where to look: Steering rack mounted crosswise under the engine bay, connected to the steering column via intermediate shaft
Ask the seller
“Do you notice any clunking through the steering wheel when going over bumps at low speed?”
“Has the power steering warning light ever appeared on the dashboard?”
“Has any steering rack work been carried out?”
CoolingCritical
EngineCritical
EngineCritical
EngineCritical
EngineCritical
SuspensionCritical
EngineMajor
TransmissionMajor
TransmissionMajor
TransmissionMajor
EngineMajor
EngineMajor
EngineMajor
EngineMajor
EngineMajor
SuspensionMajor
BrakesMajor
SuspensionMajor
EngineMajor
Fluid LeaksMajor
EngineMajor
BrakesMajor
EngineMajor
EngineMajor
EngineMinor
ElectricalMinor
26 more documented faults on the Mazda CX-9
Symptoms, what to check, where to look and what to ask the seller — for every fault above. Free with an account, no card needed. One account covers one vehicle, so make it the car you’re actually looking at.
This page covers the model. Enter the plate of the actual car you’re looking at and see its year, engine, safety rating and register flags — free, no account needed.
Like any used car, it depends on the specific example and its service history. Across the 28 documented faults for the Mazda CX-9, the recurring problem areas are engine, cooling, and suspension. A Mazda CX-9 with a full service history and no signs of the issues listed on this page can be a sound buy but each one needs to be checked individually before you commit.
What are the most common problems with a used Mazda CX-9?
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We've catalogued 28 known faults for the Mazda CX-9, covering engine, cooling, and suspension. Two are written out in full on this page. The rest — with the symptoms to notice, what to inspect, and typical repair costs for each — are free once you create an account.
How much do repairs cost on a Mazda CX-9?
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Most single repairs on the Mazda CX-9 fall between $450–$2,200 at NZ independent-workshop rates. Some of the 28 documented faults cost less and a few cost considerably more, and no one car needs them all. Knowing which ones to look for before you view is what lets you negotiate the price down or walk away.
Should I get a pre-purchase inspection on a Mazda CX-9?
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Yes. A Mazda CX-9 inspection focused on its known weak points is the single best way to avoid an expensive mistake. KickTyres gives you a guided, model-specific inspection plus a market valuation and negotiation figure for $17.90 far less than the cost of missing one of the faults on this page.